Agreed. I flew LH quiet regularly out of BEY throughout the months of July/August. I would almost always book my tickets 2 weeks in advance. I would sometimes get Z fares and sometimes get D fares. There was usually about a $1100 difference between both!!! Nevertheless, on my last trip, my TA was able to book me on a half D (BEY-FRA) and half Z (FRA-BEY) fare and saved me about $900!!! I have no idea how he managed to do that, but it is sometimes worth going through a TA as online reservations will lock you into a particular fare basis for your entire trip even if a lower fare basis is available.